Federer will play with Belinda Bencic for Switzerland.
The two will be facing off against each other at the Hopman Open on New Year's Day in a Mixed Doubles match.
Federer stressed that both players are looking for victory.
Federer and his playing partner Belinda Bencic are set to face Williams and her partner Frances Tiafoe in what is quickly becoming the most anticipated match of the New Year when the two teams face off on Tuesday.
The game was always on the racquet of Williams, who fired down 45 winners and committed 40 unforced errors during the match compared to just 17 and 19 from her the world No.54. Bencic broke back in the seventh game after a volley error from Serena and she was the player to beat in the rest of the set, breaking again at love in game nine and delivering the opener after a service victor in game 10, rattling off the last five games.
Following on from that Serena is set to make her long-awaited return to the Australian Open in mid-January, after sitting out the tournament a year ago to recover from giving birth.
Earlier, in the men's singles at the mixed team event, Federer dispatched Frances Tiafoe, 6-4, 6-1.
As it turned out, the tie was decided by the mixed doubles, after both Federer and Williams won their earlier singles matches. "Just playing someone so great, and someone you admire so much, and a match that actually means something".
" I was nervous returning because people talk about her serve so much". Roger Federer has 20 titles, a mark he reached in 2018. "You can see how focused she is and that's what I love about her".
Speaking afterwards, 20-time Grand Slam victor Federer described the chance to take on Williams - who holds the record for most Grand Slam titles among active players at 39 - as "an honour".
Defending champion Switzerland will qualify for Saturday's final if it beats Greece on Thursday.
The pair battled it out for over two hours in their first round match before Venus broke through in the sixth game of the decider to set up victory.
Williams said it was "like a dream come true".
Williams led 4-1 in the first set before Bencic fought back to win the next five games.
She is targeting Margaret Court's record of 24 Grand Slam titles and could secure that honour this season.